To clarify the spatial effect of the smallscale
deep foundation pit of utility tunnels using shield method during construction
process, a case study is conducted on nine working shaft foundation pits along
the Tongtu road utility tunnel project in the central area of Ningbo, China,
and the design of supporting structure for deep foundation pit of working shaft
is introduced. Then the threedimensional numerical
calculation model of #1 working shaft foundation pit is established using
finite element analysis method, and the deformation characteristics of the
diaphragm wall structure and the surrounding soil during the excavation of
foundation pit are analyzed by introducing the scale coefficient 〖WT５《TNR#I》〗R〖WT５《TNR》〗. The
results reveal the following: (1) In the deep soft soil layer, the influencing
ranges of spatial effect at different depths are almost the same, whereas the
influence of spatial effect on deep soil is relatively larger than shallow
soil. (2) The critical dimention value of the spatial effect can be obtained
based on numerical calculation. Within the influence range of spatial effect,
the increase of 〖WT５《TNR#I》〗R〖WT５《TNR》〗 value is nonlinear, otherwise, the 〖WT５《TNR#I》〗R〖WT５《TNR》〗 value is stable at 1.0, which agrees
plane strain assumption. (3) The calculation method of standard method is
conservative if the dimension of the long side of the foundation pit is less
than the critical value. The influence range of spatial effect can be judged in
combination with threedimensional numerical
calculation, and the support structure design can be optimized.
WANG Gaoke
.
Spatial Effect of SmallScale Deep Foundation Pit of Utility
Tunnels Using Shield Method in Soft Soil Area
[J]. Tunnel Construction, 2022
, 42(S2)
: 151
-160
.
DOI: 10.3973/j.issn.2096-4498.2022.S2.018
